The Rat Model Core (Core 9001) of the Emory University Silvio O. Conte Center for the Neuroscience of Mental Disorders (CCNMD) represents an integral component of the overall Center. This Core will serve as the source of all rodents used by individual preclinical Research Projects 1-4. This Core will produce and characterize variants of a rat early life stress (ELS) model associated with vulnerability to the development of an anxiety-and depression-like syndrome. Personnel will purchase or breed rodents, provide high quality animal care and uniformly applied neonatal manipulation protocols necessary to generate the ELS model, characterize the phenotype of all animals, ascertain the stage of the estrus cycle in adult female animals, and provide experimental manipulations as required by individual preclinical Research Projects within the Center. This ELS model consists of Long Evans rats which are exposed to different rearing conditions from postnatal days (PND) 2-12, including: (1) animal facility reared (AFR) colony controls, (2) brief handling plus 15 min maternal separation (HMS15) handling controls, (3) brief handling plus variable maternal separation (HMS180+). Comparison of data obtained from these standardized rearing conditions among the various basic Research projects of this CCNMD will permit identification of central neurocircuits and intracellular mechanisms which are impacted by early life stress and which give rise to this anxiety- and depression-like syndrome; furthermore, because the animal models will be standardized, regression modeling can be used to elucidate interactions among these CNS systems in the genesis of this condition. In addition, the efficacy of various manipulations or treatments on aspects of the anxiety- and depression-like syndrome will be tested in these models. An important aspect of these animals is comparison with the phenotype and other measures in the nonhuman primate model as well as in the human studies. To this end, Core 9001 will characterize the behavioral and HPA axis stress responsiveness of animals, provide phenotypic screening for anhedonia, anxiety-/fear-like behavior, as well as providing surgical services, resident intruder social defeat exposure, and other protocols as required by the Research Projects. This organization has the advantage of maintaining consistency in animal handling and implementation of all protocols so that each preclinical Research Project receives identically characterized and treated animals for study.